Well cementing apparatus



Patented Oct. 28, 1947 WELL CEMENTING APPARATUS John R. Baker,Philadelphia, Pa., assignor to Baker Oil Tools, 1110., Vernon, Calif., acorporation of California Application December 29, 1944, Serial No.570,392

Claims.

This invention relates to apparatus for cementing casing in well bores,and more particularly to apparatus embodying side ports through whichceme'ntitious material can be ejected for passage into the annulusbetween the casing and wall of the well bore.

It is an object of the present invention to control fluid flow throughthe side ports of easing or similar apparatus by the hydrostatic orpressure head of fluid disposed externally of the casing.

Another object of the invention is to utilize the hydrostatic head of acolumn of cementitious material, like cement slurry, placed around thestring of casing to close casing ports through which such material hasbeen ejected and thereby prevent its return flow into the casing.

A further object of the invention is to provide an improved side portedwell cementing apparatus through which cementitious material can beejected into the annulus around the casing string, in which the portsare closed after the material has been ejected to prevent subsequentpassage of fluids from the interior of the apparatus, through the portsto the exterior of the apparatus.

Still another object of the invention is to employ the hydrostatic headof a column of cementitious material placed around a string of casing toclose casing ports through which such material has been ejected and thusprevent subsequent passage of fluid from the interior of the apparatusoutwardly through the casing ports.

This invention has other objects that will become apparent from aconsideration of the embodiment shown in the drawings accompanying andforming part of the present specification. This form will now" bedescribed in detail, but it is to be understood that such detaileddescription is not to be taken in a limited sense since the scope of theinvention is best defined by the claims appended hereto.

Referring to the drawings:

Figure 1 is a partial longitudinal section of a well cementingapparatus;

Figure 2 is a view similar to Figure 1, with parts of the apparatus inanother operative position; and

Figure 3 is a View similar to Figure l, with the parts of the apparatusin still'another operative position.

The well cementing apparatus is disclosed in the drawings as a collar Aadapted to form part of a string of casing having its ends threaded toseparated upper and lower casing sections B,

C. The specific collar disclosed comprises an upper tubular member NJsecured to the upper casing section B, in which is threadedly received alower tubular member ll attached to the lower casing section C.

The lower tubular member H is provided with a plurality of ports I2,initially closed to prevent passage of fluids between the interior andexterior of the casing byan inner sleeve valve 13 having upper and lowerseals M, i5 disposed on opposite sides of the ports. This sleeve valveis held in position over the ports by one or more shear screws l6threaded into the lower tubular member II and sleeve valve [3. An outersleeve valve I1 is slidably mounted on the lower tubular member and isprovided with a plurality of ports l8 adapted to coincide with the portsl2 through the lower tubular member, in order that fluids may pass fromthe interior to the exterior of the cementing collar A. The outersleeve-valve H is movable from a position in which its ports l8 are inalignment with the lower tubular member ports I2 to a position ofdisalignment wherein the metal of the sleeve valve is disposed over thelower member ports to prevent flow of fluid therethrough. To guardagainst inadvertent rotation or angular movement of the outer sleevevalve, its upper end is provided with one or more guide slots H9 inwhich are received keys or pins 20 threaded into the lower tubularmember. This key connection i9, 20 permits longitudinal movement of theouter sleeve valve H on the lower tubular member H but prevents rotationtherebetween.

Return flow of fluid into the casing string after its ejection throughthe coinciding ports l2, i8 is precluded by a back pressure valve on theexterior of the outer sleeve valve. Ihe specific form of back pressurevalve illustrated in the drawing consists of an elastic sleeve 2! ofrubher or similar material having one end secured to the sleeve in anysuitable manner, as by the interlocking flanges 22, 23 on the sleeve Hand rubber valve member H. The back pressure valve 2i extends over theports !8 and is capable of flexing outwardly under the action of thefluid passing through the ports to discharge into the annulus betweenthe casing string and wall of the well bore. The inherent elasticity ofthe sleeve, however, causes it to close back over the ports [8 andagainst the exterior of the outer sleeve valve ll whenever the internalpressure is relieved, to prevent return flow of fluids through the portsl8, 12.

The upper tubular member it has a depending more inlet or bleeder ports26, extending through the wall of the lower tubular member at the upperend of the cylinder. The cylinder 25 contains an upper annular head orpiston 21 on the external sleeve valve I'I. Leakage in both directionsbetween this piston 21, on the one hand, and the cylinder wall 24 andexternal surface Ila of the lower tubular member, on the other hand, isprevented by outer and inner sealing rings 28, 29 disposed in generallywedge or vshaped grooves 30, 3| formed in the outer and inner surfacesof the piston. The sealing rings are circular in cross section and tendto be wedged by the tapered sides of the grooves into leakproofengagement with the surfaces of the cylinder wall 24 or lower tubularmember Ii when pressure is imposed on them either from above or below.

The external sleeve valve IT is also provided with a lower annular heador piston 32 having an inner generally wedge or V-shaped groove 33 inwhich is contained a round sealing or piston ring 34 adapted to slidablyengage the external surface Ila of the lower tubular member. Theexternal sleeve valve is also provided with intermediate generallyV-shaped grooves 35, 35 above and below the sleeve ports IS, in whichare contained round sealing rings 31, 38 slidably engageable with theexternal surface Ila of the lower tubular member.

The apparatus forms part of the casing string and is lowered therewithinto the well bore with its parts in the relative positions shown inFigure 1, in which the inner sleeve valve I3 is disposed over the lowermember ports I2, and the external sleeve valve I1 is in its lowermostposition resting upon a shoulder 39 on the lower tubular member with itsports I8 coinciding, or communicating with, the ports I2 through thelower member.

When fluid is to be ejected from the apparatus,

a suitable bridging member, such as a ball 40, is lowered or allowed togravitate through the fluid in the well casing until it comes to rest onthe inner sleeve valve I3, closing its central passage 4| and enablingsufficient pressure to be built up in the fluid in the casing stringthereabove to shear the screws I6 and move the inner sleeve valve :3 andball 40 downwardly to a position below the ports I2. Fluid can then passoutwardly through the aligned open ports I2, I8, flexing the elasticback pressure valve 2! in an outward direction and passing outwardlyinto the annulus around the casing.

In the event that the external sleeve valve Il may have shifted upwardlyduring lowering of the casing string in the well bore, the pressurebuilt up inside the casing after seating of the bridging member 40 onthe inner sleeve it acts through the inlet port 26 on the upper end ofthe piston 21, to shift the outer sleeve valve Il downwardly intocontact with the shoulder 33 on the lower tubular member, to realign thesleeve ports l8 with the lower member ports l2 and thus allow outwardflow of fluid into the annulus around the casing, in the manneraforementioned.

The fluid ejected from the casing may consist of a cementious material,such as cement slurry, and this material rises in the annulus around thecasing to the desired height. Usually only a small quantity or height ofcement slurry is allowed to remain in the casing string above the portsI2, producing a back pressure elfect upon relieving of the pressurewithin the casing, caused by the fact that the outer column of cementslurry extends much higher than the slurry remaining inside the casing,and by the further fact that the specific gravity of the cement slurryis much greater than that of the water or other displacement fluid inthe casing used to eject the slurry from the casing string through theopen ports. The greater hydrostatic or pressure head of the cementslurry externally of the casing presses the elastic back pressure valve2| firmly against the exterior of the outer sleeve valve 11, and overthe sleeve valve. ports I8, to prevent return flow of the cement slurryinto the casing.

The greater hydrostatic head of the cement slurr on the exterior of thecasing string is also employed to shift the outer sleeve valve I Ibodily along the lower tubular member II to disalign the ports I8, I2and provide a further means for preventing return flow of cement slurryfrom the annulus around the casing into the casing string. Such shiftingof the outer sleeve valve H is also availed of to prevent passage offluid from the interior of the casing to its exterior through the portsi2, as will now be described.

It is to be noted that the hydrostatic head of fluid on the exterior ofthe casing can act longitudinally on the outer sleeve valve H in bothdirections. This unit hydrostatic head or pressure P is capable ofacting on the underside of the upper piston 21 across its pressureactive area b, to urge the outer sleeve I! in an upward direction;across the pressure active surface 0 extending around the elastic backpressure valve, to urge the outer sleeve l l in a downward direction;and across the pressure active undersurf'ace a of the lower annularpiston 32 tourge the outer sleeve valve in an upward direction. Theresultant total force tends to shift the outer sleeve valve in an upwarddirection, and is equal to P(a+bc) The force tending to shift the outersleeve H in a downward direction is represented by the unit hydrostatichead or pressure p inside the casing acting over the area (2 at theupper surface of the upper piston 21. So long as the resultant forceacting upwardly on the outer sleeve valve is greater than the downwardforce from within the casing acting downwardly on the sleeve valve, theexternal hydrostatic head elevates the sleeve valve and shifts it toclosed position over the ports I2 in the lower tubular member. Expressedin another manner, the hydrostatic head of fluid on the exterior of thecasing will shift the outer sleeve valve IT in an upward directionwhenever P(a+b c) is greater than pwd.

The relieving of the pressure within the casing, following ejection ofall desired cement slurry from the ports I2, I8, will insure a largeexcess of external elevating force acting on the outer sleeve valve I 7over the internal lowering force. To take a simple design, if it isassumed that the area b equals the area 0, and. that the area (1 equalsthe area d, the outer sleeve valve wiil be elevated whenever thehydrostatic head externally of the casing string is greater than thatinternally of the casing string.

It is to be noted that elevation of the outer sleeve valve I! disposesthe intermediate lower seal 33 above the ports I2 extending through thelower tubular member. The bottom sealing ring '34 will remainbelow thelatter ports, thus providing an imperforate sleeve portion disposed overthe ports 12 with sealing rings on opposite sides of these ports,preventing passage of fluid under pressure from the interior of thecollar to its exterior. The back pressure valve 2| prevents return flowof fluid from the exterior of the casing into the collar A. As a result,the ports 12 are closed to prevent the passage of fluid between theexterior and the interior of the casing string in both directions.

A positive port closure has thus been obtained against flow of fluid inboth directions, The pressure of the fluid inside the casing may actthrough the inlet ports 26 and tend to shift the outer sleeve IT in adownward direction to realign the ports I8, 12, but ordinarily any suchpressure would not be imposed until after the cement slurry has set andhardened around the casing and the outer sleeve valve [1, securelylocking the latter in closed position and preventing its downwardshifting. However, as a precautionary measure, to insure that pressureexerted through the inlet port 26 will not shift the outer sleeve valve11 to port aligning position, the upper head 21 on the sleeve may beprovided with an inner groove 42 carrying a split contractile ring 43adapted to snap into a companion groove 44 formed on the exterior of thelower tubular member upon elevation of the outer sleeve valve 11 to portclosing position. 'The engagement of the split ring 43 in the groove 44will lock the outer sleeve valve ll against movement in a downwarddirection and prevent pressure exerted through the inlet port 26 from soshifting the outer sleeve member.

I claim:

1. An apparatus including a tubular member having a port and adapted toform part of a casing string, a back-pressure valve for preventingpassage of fluid through said port from the exterior of said apparatusto the interior of said tubular member, a valvemember on said tubularmember for controlling flow of fluid through said port, said valvemember being so constructed and arranged as to be shifted on saidtubular member by fluid pressure externally of said apparatus to aposition closing saidport to the passage of fluid from the interior ofsaid tubular member to the exterior of said apparatus.

2. An apparatus including a tubular'member having a port and. adapted toform part of a casing string, a back-pressure valve for preventingpassage of fluid through said port from the exterior of said apparatusto the interior of said tubular member, a sleeve valve on said tubularmember for opening and closing said port to the passage of fluid fromwithin said tubular member to the exterior of said apparatus, saidsleeve valve having a pressure active surface subject to the action offluid pressure externally of said apparatus to slide said sleeve valveon said tubular member to port closing position to prevent passage offluid from the interior of said tubular member to the exterior of saidapparatus.

sage of fluid from within said tubular member to the exterior of saidapparatus, said sleeve valve having a pressure active surface at one endthereof communicable with the interior of said tubular member to enablefluid pressure internally of said tubular member to shift said valve toport opening position, saidsleeve valve having a fluid pressure activesurface on its other end communicable with the exterior of saidapparatus to enable fluid pressure externally of said apparatus to shiftsaid valve on said tubular member to port closing position, and backpressure valve means for preventing passage of fluid from externallyrofsaid apparatus through said port.

4. An apparatus including a tubular member having a port and. adapted toform part of a casing string, a sleeve valve on said tubular member foropening and closing said port to the passage of fluid from within saidtubular member to the exterior of said apparatus, a back-pressure valvemounted on said sleeve valve for preventing passage of fluid throughsaid port from the exterior of said apparatus to the interior of saidtubular member, said sleeve valve having a pressure active surfacesubject to the action of fluid pressure externally of said apparatus toshift said sleeve valve on said tubular member to port closing positionto prevent passage of fluid from the interior of said tubular member tothe exterior of said apparatus.

5. An apparatus including a tubular member having a port and adapted toform part of a casing string, a sleeve valve on said tubular memberhaving a port adapted to align with said tubular member port to permitpassage of fluid from within said tubular member to the exterior of saidapparatus, a back-pressure valve on said sleeve valve for closing saidsleeve valve port and prevent passage of fluid from the exterior of saidapparatus to the interior of said tubular member, said sleeve valvehaving a pressure active surface subjectto the action of fluid pressureexternally of said apparatus to shift said. sleeve valve on said tubularmember to disalign said ports and prevent passage of fluid from theinterior of said tubular member to the exterior of said apparatus.

' JOHN R. BAKER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,187,482 Baker et al Jan. 16,1940 2,330,267 Burt et al. Sept. 28, 1943 2,344,120 Baker Mar, 14, 1944'1,793,780 Daniel Feb. 24, 1931 1,832,088 Boynton Nov. 17, 1931

